INSTRUCTION MANUAL.

DOUBLE PIPE HEAT EXCHANGER

SET UP

DESCRIPTION

SPECIFICATIONS

INSTALLATION REQUIRWMWNTS

INSTALLATION AND CONNECTIONS

PRECAUTIONS

TROUBLE SHOOTING

EXPREMENTATION

THEORY

OPERATING PROCEDURE’

SYSTEM CONSTANTS

OBSERVATION TABLE

CALCULATIONS

DOUBLE PIPE HEAT EXCHANGER.

AIM: To determine the overall and firm heat transfer coefficient in double

pipe heat exchanger.

INTRODUCTION :

The cost of heat exchanger is directly proportion to the heat transfer area,

which is inversely proportional to the overall heat transfer coefficient for the

given heat transfer rate. Hence design engineer shall always try to keep high

overall heat transfer coefficient.

THEORY:

The overall heat transfer coefficient is related to two firm heat transfer

coefficient by following equation,

1 = 1 = Ai

--- --- -----

Ui hi hoAo

Which shows that if ho is very small compared to hi then Ui will be controlled

by ho and hence shall be small. As practical example, the film heat transfer

coefficient for the air stream is of the order of 50 and that for the condensing

steam is of the order of the magnitude of 5,000 tp 10,000 K-cal/ (hr) (m²) ( c)

the overall heat transfer coefficient is essentially equal to the individual

coefficient for the cold water. The capacity of a unit area of heating surface

will be low, and many meters of tube will be required to provide reasonable

capacity.

Here in this case :

π D² X L (Inner tube)

De = -------

4

PROCEDURE :

1. Admit cold air at fixed flow rat.

2. Admit hot water at 65 to 80 C inside the tube at definate flow rate so

that turbulent conditions are achieved.

3. At steady state, note down the flow rates and temperature of the air and

hot water, note down flow rates of water and air.

4. Change flow rate of hot water maintaining flow rate of air the same.

5. Repeat above procedure for atlas four readings.

OBSERVATIONS:

SR.

NO.

COLD WATER HOT WATER

Flow rate

Mc,Kg/hr.

Inlet temp.

t ci c.

Outlet

Temp. t ci

C

Flow rate

Mc, kg/hr

Inlet temp.

t hi c

Outlet

temp. t ho

c

RESULTS:

SR

NO.

Overall h.t.c. Ui

Kcal

Hr.m².º C

1/Ui 1

0.8

Vi

Hi k-cal

Hr. m².º C

Remarks

1.

2.

3.

4.

5.